function ydot = SIP_ode(t,y,K)
x = y(1);
xD = y(2);
theta = y(3);
thetaD = y(4);
v = -K*[xD; theta; thetaD];
ydot(1) = xD;
ydot(2) = -1/290*(40000*v-40000*xD-1160*sin(theta)*thetaD^2+2900*cos(theta)*v-2900*cos(theta)*thetaD+28449*cos(theta)*sin(theta))/(-23+10*cos(theta)^2);
ydot(3) = thetaD;
ydot(4) = 1/1160*(-400000*cos(theta)*v+400000*cos(theta)*xD+11600*cos(theta)*sin(theta)*thetaD^2-66700*v+66700*thetaD-654327*sin(theta))/(-23+10*cos(theta)^2);
ydot = ydot(:);